Texas Instruments CBR 2 manual Hints for effective data collection cont, Speed of sound

Hints for effective data collection (cont.)

Speed of sound

The approximate distance to the object is calculated by assuming a nominal speed of sound. However, actual speed of sound varies with several factors, most notably the air temperature.

The CBR 2™ motion detector has a built-in temperature sensor to automatically compensate for changes in the speed of sound due to the temperature of the surrounding air. The temperature conversion from 0° to 40° Celsius, at standard pressure, is fairly linear at about +0.6 meters/second per degree Celsius. The speed of sound increases from about 331 meters/second at 0° Celsius to about 355 meters/second at 40° Celsius. These speeds assume a relative humidity of 35% (dry air).

When using the EasyData App with the CBR 2™ motion detector, this temperature compensation will take place when collecting motion data. The sensor is located underneath the holes on the back of the CBR 2™ motion detector; therefore, when collecting data, do not cover these holes with something that is of a different temperature from the surrounding ambient temperature.

Using the CBR 2™ sonic motion detector without the EasyData application

You can use the CBR 2™ unit as a sonic motion detector with a CBL 2™ system or with programs other than EasyData.

Using the I/O unit-to-unit cable, the CBR 2™ motion detector can be used with graphing calculators that do not have the EasyData App installed but do have the CBL/CBR App and/or the RANGER program. The CBR 2™ motion detector will provide the same functionality as a CBR™ motion detector when sample data is collected using the CBL/CBR App and/or the RANGER program.

The CBL/CBR App can be used on most older TI-83 Plus calculators. The CBL/CBR App is available for downloading at education.ti.com and allows you to collect motion data using the I/O unit-to-unit cable on the CBR 2™ motion detector.

The RANGER program, which is part of the CBL/CBR App and available for other calculators, allows you to collect motion data using the I/O unit-to-unit cable. Many TI Explorations workbooks use the RANGER program. (The RANGER program is the only program available for use with the TI-89, TI-92 Plus, TI-89 Titanium, and Voyage™ 200 to perform activities like Ball Bounce and Graph Match.)

You can also use CBR 2™ unit as a motion sensor with your CBL 2™ data collection device. Use the DataMate App that comes with the CBL 2™ system to operate the CBR 2™ motion detector through a CBL 2™ system. A special CBL-to-CBRcable is required to use this system. For more information about this cable visit the TI webstore at education.ti.com.

© 1997, 2004, 2006 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBR 2™ SONIC MOTION DETECTOR 9